1. Field of the Invention
The present invention relates to an ink-jet printhead and a method of manufacturing the ink-jet printhead, and more particularly, to an ink-jet printhead including a nozzle plate having an excellent hydrophobic property and an excellent adhering property, and a method of manufacturing the ink-jet printhead.
2. Description of the Related Art
In Ink-jet printheads, an electro-thermal transducer (ink jet type) generating bubbles in ink using a heat source and ejecting ink droplets by a force generated by the bubbles is mainly used.
FIG. 1 is a perspective view schematically illustrating a structure of a conventional ink-jet printhead, and FIG. 2 is a cross-sectional view of the conventional ink-jet printhead shown in FIG. 1.
As shown in FIGS. 1 and 2, the conventional ink-jet printhead includes a manifold (not shown) to which ink is supplied, a substrate 1 on which a heater 12 and a passivation layer 11 protecting the heater 12 are formed, a passage plate 2 having a passage 22 and an ink chamber 21 formed on the substrate 1, and a nozzle plate 3 which is formed on the passage plate 2 and in which an orifice 31 corresponding to the ink chamber 21 is formed.
In general, the passage plate 2 and the nozzle plate 3 are formed by a photolithography process using polyimide. In the conventional ink-jet printhead, the passage plate 2 and the nozzle plate 3 are formed of the same material, for example, the polyimide. Due to a weak adhering property of the polyimide, the nozzle plate 3 may be detached from the passage plate 2.
In order to solve the above problem, in a conventional method of manufacturing the conventional ink-jet printhead, if the passage plate 2 and the nozzle plate 3 are different layers formed of the polyimide as described above, the passage plate 2 and the nozzle plate 3 are separately manufactured and are then attached to the substrate 1. In this method, due to problems including a structural misalignment, the nozzle plate 3 cannot be attached to the substrate 1 in a form of a wafer and should be attached to each chip separated from the wafer, thereby creating a disadvantage in productivity.
Meanwhile, in another conventional method of manufacturing the ink-jet printhead, a mold layer used as a sacrifice layer to form a chamber and a passage, is formed of a photoresist, then a passage plate and a nozzle plate made of the polyimide are formed on the mold layer as a single layer, and the sacrifice layer is then removed, thereby forming the chamber and the passage. If the passage plate and the nozzle plate are formed using the mold layer, the polyimide cannot be baked at a temperature high enough, so that the mold layer can be protected.
The nozzle plate of the ink-jet printhead directly faces a recording sheet and possesses several factors that influence ejection of ink droplets ejected through a nozzle. Among these factors is a hydrophobic property on a surface of the nozzle plate. If the hydrophobic property is almost non-existent, that is, if the surface of the nozzle plate has a hydrophile property, some of the ink ejected through the nozzle flows out the surface of the nozzle plate, such that the surface of the nozzle plate is contaminated and a size, a direction, and a speed of the ink droplets ejected are not uniform. As described above, the nozzle plate formed of the polyimide has the hydrophile property and thus has the above-mentioned problems. In order to solve these problems caused by the hydrophile property, in general, a coating layer used to form the hydrophobic property should be additionally formed on the surface of the nozzle plate formed of the polyimide. Metal, such as plated nickel (Ni), gold (Au), palladium (Pd), or tantalum (Ta), or a perfluoronated alkane, and silane compound having a high hydrophobic property, such as fluoronated carbon (FC), F-silane, or diamond like carbon (DLC), are used for the coating layer. The hydrophobic coating layer may be formed using a liquid method, such as spray coating or spin coating, and is deposited using a dry method, such as plasma enhanced chemical vapor deposition (PECVD) or sputtering. As a result, the coating layer used to form the hydrophobic property increases manufacturing costs.